Revisiting homogeneous electron gas in pursuit of properly normed ab initio Eliashberg theory

Article

关键词: TRANSITION-TEMPERATURE;    LATTICE-VIBRATIONS;    EXCHANGE;    GW;   

DOI  :  10.1103/PhysRevB.105.104510

来源: SCIE

【 摘 要 】

We address an issue of how to accurately include the self-energy effect of the screened electron-electron Coulomb interaction in phonon-mediated superconductors from first principles. In the Eliashberg theory for superconductors, self-energy is usually decomposed using the 2 x 2 Pauli matrices in the electron-hole space. We examine how the diagonal (sigma(0) and sigma(3)) components resulting in the quasiparticle correction to the normal state, Z and chi terms, behave in the homogeneous electron gas in order to establish a norm of treating those components in real metallic systems. Within the G(0)W(0) approximation, we point out that these components are nonanalytic near the Fermi surface but their directional derivatives and resulting corrections to the quasiparticle velocity are, nevertheless, well defined. Combined calculations using the G(0)W(0) approximation and Eliashberg equations show us that the effective mass and pairing strength strikingly depend on both Z and chi in different manners. The calculations without the numerically demanding chi term is thus shown to be incapable of describing the homogeneous electron gas limit. This result poses a challenge to accurate first-principles Eliashberg theory.

【 授权许可】

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